Demon Sword Master of Excalibur Academy, Vol. 6 (light novel)

THE PRICE OF VENGEANCE Nine years ago, Sakuya lost her home and sister to a powerful Void Lord. She's dedicated her life to fighting the Voids ever since. However, when a group of the Sakura Orchid's greatest fighters, the Kenki Gathering, contact her with a plan to use the Seventh Assault Garden as bait for the Void Lord, she's left in a difficult position. While she wants revenge, it can't come at the cost of her new home, but Sakuya can't stop the Kenki Gathering by herself. Fortunately, she knows someone who might be able to help...a Dark Lord!